1. Field of the Invention
This invention relates to a method for using an orally administered sustained release ranolazine dosage formulations to maintain human ranolazine plasma levels at therapeutic levels.
2. Description of the Art
U.S. Pat. No. 4,567,264, the specification of which is incorporated herein by reference, discloses ranolazine, (xc2x1)-N-(2,6-dimethylphenyl)-4-[2-hydroxy-3-(2-methoxyphenoxy)-propyl]-1-piperazineacetamide, and its pharmaceutically acceptable salts, and their use in the treatment of cardiovascular diseases, including arrhythmias, variant and exercise-induced angina, and myocardial infarction.
U.S. Pat. No. 5,506,229, which is incorporated herein by reference, discloses the use of ranolazine and its pharmaceutically acceptable salts and esters for the treatment of tissues experiencing a physical or chemical insult, including cardioplegia, hypoxic or reperfusion injury to cardiac or skeletal muscle or brain tissue, and for use in trasplants. Conventional oral and parenteral formulations are disclosed, including controlled release formulations. In particular, Example 7D of U.S. Pat. No. 5,506,229 describes a controlled release formulation in capsule form comprising microspheres of ranolazine and microcrystalline cellulose coated with release controlling polymers.
The presently preferred route of administration for ranolazine and its pharmaceutically acceptable salts and esters is oral. A typical oral dosage form is a compressed tablet, a hard gelatin capsule filled with a powder mix or granulate, or a soft gelatin capsule (softgel) filled with a solution or suspension. U.S. Pat. No. 5,472,707, the specification of which is incorporated herein by reference, discloses a high-dose oral formulation employing supercooled liquid ranolazine as a fill solution for a hard gelatin capsule or softgel.
As set forth in application Example 3, the initial trials of ranolazine on humans suffering from angina were failures. The trials used an immediate release of ranolazine formulation at a dose level of 120 mg taken three times daily. Based upon the initial experiments, it was uncertain whether or not ranolazine could be given to humans in an amount and mode that is effective against angina.
One problem with conventional oral dosage formulations is that they are not ideally suited to ranolazine and its pharmaceutically acceptable salts, because the solubility of ranolazine is relatively high at the low pH that occurs in the stomach. Furthermore ranolazine also has a relatively short plasma half-life. The high acid solubility property of ranolazine results in rapid drug absorption and clearance, causing large and undesirable fluctuations in plasma concentration of ranolazine and a short duration of action, thus necessitating frequent oral administration for adequate treatment.
There is therefore a need for a method for administering ranolazine in an oral dosage form once or twice daily that provides therapeutically effective plasma concentrations of ranolazine for the treatment of angina in humans.
In a first aspect, this invention is a sustained release ranolazine formulation where the majority of the formulation consists of active ranolazine.
In another aspect, this invention is a method of treating a human patient who is suffering from angina or other coronary disorders by administering a sustained release ranolazine formulation to the patient once or twice daily.
In yet another aspect, this invention is a method for treating a mammal having a disease state for which the administration of ranolazine is indicated, comprising the once or twice-daily administration of sustained release ranolazine formulation of this invention in a manner that maintains plasma ranolazine close to minimal effective levels without peak fluctuations.
Still another aspect of this invention is a method of maintaining useful levels of ranolazine in human plasma by administering a ranolazine containing dosage form only one or twice daily.
This invention includes methods for treating a human patient suffering from a cardiovascular disease selected from arrhythmias, variant and exercise-induced angina, and myocardial infarction. The method includes administering a sustained release pharmaceutical dosage form including at least 50% by weight ranolazine in no more than two tablets per dose to the human patient to maintain ranolazine plasma levels in the human patient of from about 550 to about 7500 ng base/mL for at least 24 hours wherein the dose is administered at a frequency selected from once, twice and three times over 24 hours.
This invention further includes methods for treating a human patient suffering from a cardiovascular disease selected from arrhythmias, variant and exercise-induced angina, and myocardial infarction. The method includes administering a sustained release, pharmaceutical dosage form including from about 70 to about 80% by weight ranolazine in no more than two tablets per dose to the human patient to maintain ranolazine plasma levels in the human patient of from about 1000 to about 3900 ng base/mL for at least 24 hours wherein the dose is administered at a frequency selected from one and two times over 24 hours.
This invention also includes pharmaceutical dosage forms comprising at least about 50 wt % ranolazine and at least one pH dependent binder that inhibits the release of ranolazine from the sustained release dosage form when the sustained release dosage form is subjected to an aqueous environment having a pH of the stomach and that promotes the release of a therapeutic amount of ranolazine in an aqueous solution having a pH above about 4.5.
xe2x80x9cRanolazinexe2x80x9d is the compound (xc2x1)-N-(2,6-dimethylphenyl)-4-[2-hydroxy-3-(2-methoxphenoxy)propyl]-1-piperazine-acetamide, or its enantiomers (R)-(+)-N-(2,6-dimethylphenyl)-4-[2-hydroxy-3-(2-methoxyphenoxy)-propyl]-1-piperazineacetamide, and (S)-(xe2x88x92)-N-(2,6-dimethylphenyl)-4-[2-hydroxy-3-(2-methoxyphenoxy)-propyl]-1-piperazineacetamide and their pharmaceutically acceptable salts, and mixtures thereof. Unless otherwise stated the ranolazine plasma concentrations used in the specification and examples refers to ranolazine free base.
xe2x80x9cOptionalxe2x80x9d and xe2x80x9coptionallyxe2x80x9d mean that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event or circumstance occurs and instances in which it does not. For example, xe2x80x9coptional pharmaceutical excipientsxe2x80x9d indicates that a formulation so described may or may not include pharmaceutical excipients other than those specifically stated to be present, and that the formulation so described includes instances in which the optional excipients are present and instances in which they are not.
xe2x80x9cTreatingxe2x80x9d and xe2x80x9ctreatmentxe2x80x9d refer to any treatment of a disease in a mammal, particularly a human, and include:
(i) preventing the disease from occurring in a subject which may be predisposed to the disease but has not yet been diagnosed as having it;
(ii) inhibiting the disease, i.e., arresting its development; or
(iii) relieving the disease, i.e., causing regression of the disease.
xe2x80x9cImmediate releasexe2x80x9d (xe2x80x9cIRxe2x80x9d) refers to formulations or dosage units that rapidly dissolve in vitro and are intended to be completely dissolved and absorbed in the stomach or upper gastrointestinal tract. Conventionally, such formulations release at least 90% of the active ingredient within 30 minutes of administration.
xe2x80x9cSustained releasexe2x80x9d (xe2x80x9cSRxe2x80x9d) refers to formulations or dosage units of this invention that are slowly and continuously dissolved and absorbed in the stomach and gastrointestinal tract over a period of about six hours or more. Preferred sustained release formulations are those exhibiting plasma concentrations of ranolazine suitable for no more than twice daily administration with two or less tablets per dosing as described below.
Plasma ranolazine concentration is a mean concentration determined by analyzing the concentration of ranolazine in as few as five to as many as ten humans who are on the same dosing schedule. It is important that the ranolazine concentration is a mean value because of variances in ranolazine concentrations in individuals that may be caused by differences in weight, metabolism, or disease states which may cause one person to metabolize ranolazine faster or slower than an average person. The plasma ranolazine levels are determined from drawn blood onto heparin.
Definitions of other terms used in this application are:
ANOVA=analysis of variance
ATP=adenosine triphosphate
ECG=electrocardiographic
ETT=exercise treadmill test
PDH=pyruvate dehydrogenase
Cmax=maximum concentration
Ctrough=residual concentration at 8 hours post-dose for IR formulations and 12 hours post-dose for SR formulations A-C of Example 2.
tid=three times per day
bid=twice daily
Cx=concentration at time x
Tmax=time to maximum concentration
AUCx=area under the curve after x hours or time interval
Percentages given are percentages by weight, unless otherwise stated. This invention involves sustained release ranolazine dosage forms as well as methods for administering sustained release ranolazine dosage forms of this invention to provide for therapeutic plasma levels of ranolazine.
The sustained release ranolazine formulations of this invention are preferably in the form of a compressed tablet comprising an intimate mixture of ranolazine and a partially neutralized pH-dependent binder that controls the rate of ranolazine dissolution in aqueous media across the range of pH in the stomach (typically approximately 2) and in the intestine (typically approximately about 5.5).
To provide for a sustained release of ranolazine, one or more pH-dependent binders are chosen to control the dissolution profile of the ranolazine formulation so that the formulation releases ranolazine slowly and continuously as the formulation passed through the stomach and gastrointestinal tract. The dissolution control capacity of the pH-dependent binder(s) is particularly important in a sustained release ranolazine formulation because a sustained release formulation that contains sufficient ranolazine for twice daily administration may cause untoward side effects if the ranolazine is released too rapidly (xe2x80x9cdose-dumpingxe2x80x9d).
Accordingly, the pH-dependent binders suitable for use in this invention are those which inhibit rapid release of drug from a tablet during its residence in the stomach (where the pH is-below about 4.5), and which promotes the release of a therapeutic amount of ranolazine from the dosage form in the lower gastrointestinal tract (where the pH is generally greater than about 4.5). Many materials known in the pharmaceutical art as xe2x80x9centericxe2x80x9d binders and coating agents have the desired pH dissolution properties. These include phthalic acid derivatives such as the phthalic acid derivatives of vinyl polymers and copolymers, hydroxyalkylcelluloses, alkylcelluloses, cellulose acetates, hydroxyalkylcellulose acetates, cellulose ethers, alkylcellulose acetates, and the partial esters thereof, and polymers and copolymers of lower alkyl acrylic acids and lower alkyl acrylates, and the partial esters thereof.
Preferred pH-dependent binder materials which can be used in conjunction with ranolazine to create a sustained release formulation are methacrylic acid copolymers. Methacrylic acid copolymers are copolymers of methacrylic acid with neutral acrylate or methacrylate esters such as ethyl acrylate or methyl methacrylate. A most preferred copolymer is methacrylic acid copolymer, Type C, USP (which is a copolymer of methacrylic acid and ethyl acrylate having between 46.0% and 50.6% methacrylic acid units). Such a copolymer is commercially available, from Rxc3x6hm Pharma as Eudragit(copyright) L 100-55 (as a powder) or L30D-55 (as a 30% dispersion in water). Other pH-dependent binder materials which may be used alone or in combination in a sustained release ranolazine dosage form include hydroxypropyl cellulose phthalate, hydroxypropyl methylcellulose phthalate, cellulose acetate phthalate, polyvinylacetate phthalate, polyvinylpyrrolidone phthalate, and the like. One or more pH-dependent binders are present in the ranolazine dosage forms of this invention in an amount ranging from about 1 to about 20 wt %, more preferably from about 5to about 12wt % and most preferably about 10 wt %.
One or more pH-independent binders may be in used in sustained release ranolazine oral dosage forms. It is to be noted that pH-dependent binders and viscosity enhancing agents such as hydroxypropyl methylcellulose, hydroxypropyl cellulose, methylcellulose, polyvinylpyrrolidone, neutral poly(meth)acrylate esters, and the like, do not themselves provide the required dissolution control provided by the identified pH-dependent binders. The pH-independent binders are present in the formulation of this invention in an amount ranging from about 1 to about 10 wt %, and preferably in amount ranging from about 1 to about 3 wt % and most preferably about 2.0 wt %.
As shown in Table 1, ranolazine is relatively insoluble in aqueous solutions having a pH above about 6.5, while the solubility begins to increase dramatically below about pH 6.
Increasing the pH-dependent binder content in the formulation decreases the release rate of ranolazine from the formulation at pH is below 4.5 typical of the pH found in the stomach. The enteric coating formed by the binder is less soluble and increases the relative release rate above pH 4.5, where the solubility of ranolazine is lower. A proper selection of the pH-dependent binder allows for a quicker release rate of ranolazine from the formulation above pH 4.5, while greatly affecting the release rate at low pH. Partial neutralization of the binder facilitates the conversion of the binder into a latex like film which forms around the individual ranolazine granules. Accordingly, the type and the quantity of the pH-dependent binder and amount of the partial neutralization composition are chosen to closely control the rate of dissolution of the ranolazine from the formulation.
The dosage forms of this invention should have a quantity of pH-dependent binders sufficient to produce a sustained release formulation from which the release rate of ranolazine is controlled such that at low pHs (below about 4.5) the rate of dissolution is significantly slowed. In the case of methacrylic acid copolymer, type C, USP (Eudragit(copyright) L 100-55), a suitable quantity of pH-dependent binder is between 5% and 15%. The pH dependent binder will typically have from about 1 to about 20% of the binder methacrylic acid carboxyl groups neutralized. However, it is preferred that the degree of neutralization ranges from about 3 to 6%.
The sustained release formulation may also contain pharmaceutical excipients intimately admixed with the ranolazine and the pH-dependent binder. Pharmaceutically acceptable excipients may include, for example, pH-independent binders or film-forming agents such as hydroxypropyl methylcellulose, hydroxypropyl cellulose, methylcellulose, polyvinylpyrrolidone, neutral poly(meth)acrylate esters (e.g. the methyl methacrylate/ethyl acrylate copolymers sold under the trademark Eudragit(copyright) NE by Rxc3x6hm Pharmal, starch, gelatin, sugars, carboxymethylcellulose, and the like. Other useful pharmaceutical excpients include diluents such as lactose, mannitol, dry starch, microcrystalline cellulose and the like; surface active agents such as polyoxyethylene sorbitan esters, sorbitan esters and the like; and coloring agents and flavoring agents. Lubricants (such as talc and magnesium stearate) and other tableting aids are also optionally present.
The sustained release ranolazine formulations of this invention have a ranolazine content of above about 50% by weight to about 95% or more by weight, more preferably between about 70% to about 90% by weight and most preferably from about 70 to about 80% by weight; a pH-dependent binder content of between 5% and 40%, preferably between 5% and 25%, and more preferably between 5% and 15%; with the remainder of the dosage form comprising pH-independent binders, fillers, and other optional excipients.
Particularly preferred sustained release ranolazine formulations of this invention consist, essentially of:
The sustained release ranolazine formulations of this invention are prepared as follows: ranolazine and pH-dependent binder and any optional excipients are intimately mixed (dry-blended). The dry-blended mixture is then granulated in the presence of an aqueous solution of a strong base which is sprayed into the blended powder. The granulate is dried, screened, mixed with optional lubricants (such as talc or magnesium stearate), and compressed into tablets. Preferred aqueous solutions of strong bases are solutions of alkali metal hydroxides, such as sodium or potassium hydroxide, preferably sodium hydroxide, in water (optionally containing up to 25% of water-miscible solvents such as lower alcohols).
The resulting ranolazine containing tablets may be coated with an optional film-forming agent, for identification, taste-masking purposes and to improve ease of swallowing. The film forming agent will typically be present in an amount ranging from between 2% and 4% of the tablet weight. Suitable film-forming agents are well-known to the art and include hydroxypropyl methylcellulose, cationic methacrylate copolymers (dimethylaminoethyl methacrylate/methyl-butyl methacrylate copolymersxe2x80x94Eudragit(copyright) Exe2x80x94Rxc3x6hm Pharma), and the like. These film-forming agents may optionally contain colorants, plasticizers, and other supplemental ingredients.
The compressed tablets preferably have a hardness sufficient to withstand 8 Kp compression. The tablet size will depend primarily upon the amount of ranolazine in the tablet. The tablets will include from 300 to 1100 mg of ranolazine free base. Preferably, the tablets will include amounts of ranolazine free base ranging from 400-600 mg, 650-850 mg, and 900-1100 mg.
In order to influence the dissolution rate, the time during which the ranolazine containing powder is wet mixed is controlled. Preferably the total powder mix time, i.e. the time during which the powder is exposed to sodium hydroxide solution, will range from 1 to 10 minutes and preferably from 2 to 5 minutes. Following granulation, the particles are removed from the granulator and placed in a fluid bed dryer for drying at about 60xc2x0 C.
Surprisingly, it has been found that these methods produce sustained release ranolazine formulations that provide lower peak plasma ranolazine levels and yet effective plasma concentrations of ranolazine for up to 12 hours and more after administration, when the ranolazine used as its free base, rather than as the more pharmaceutically common ranolazine dihydrochloride salt or as another salt or ester. The use of ranolazine free base affords at least one advantage: The proportion of ranolazine in the tablet can be increased, since the molecular weight of ranolazine free base is only 85% that of ranolazine dihydrochloride. In this manner, delivery of an effective amount of ranolazine is achieved while limiting the physical size of the dosage unit.
Another advantage of sustained release ranolazine formulations of this invention is that they are prepared by a process that essentially involves only water as a solvent, and utilizes standard pharmaceutical processing techniques and equipment.
The sustained release ranolazine formulations of this invention can be used for treating cardiovascular diseases, including arrhythmias, variant and exercise-induced angina, and myocardial infarction; treatment of tissues experiencing a physical or chemical insult, including cardioplegia, hypoxic or reperfusion injury to cardiac or skeletal muscle or brain tissue, and ischemia; and peripheral arterial diseases, such as intermittent claudication. It is most preferred that the sustained release dosage formulation be used as a mammalian anti-anginal agent and most preferably as a human anti-anginal agent.
The oral sustained release ranolazine dosage formulations of this invention are administered one, twice; or three times in a 24 hour period in order to maintain a plasma ranolazine level above the threshold therapeutic level and below the maximally tolerated levels, of between about 550 and 7500 ng base/mL in a patient. This corresponds to an amount of ranolazine 2 HCl ranging from about 644 ng/mL to about 8782 ng/mL. Furthermore, the timing of the oral ingestion of the ranolazine oral dosage forms should be controlled to insure that the plasma ranolazine level does not exceed about 7500 ng base/mL and preferably so that the plasma ranolazine level does not exceed about 5000 ng base/mL an most preferably so that is does not exceed 3800 ng base/mL. In some instances it may be beneficial to limit the peak plasma ranolazine level to no more than about ng base/mL. At the same time, the plasma trough ranolazine levels should preferably not fall below about 1000 ng base/mL, and in some instances should not fall below 1700 ng base/mL.
In order to achieve the preferred plasma ranolazine level of from about 1000 to about 3800 ng base/mL, it is preferred that the oral ranolazine dosage forms described herein are administered once or twice daily. If the dosage forms are administered twice daily, then it is preferred that the oral ranolazine dosage forms are administered at about twelve hour intervals.
In addition to formulating and administering oral sustained release dosage forms of this invention in a manner that controls the plasma ranolazine levels, it is also important to minimize the difference between peak and trough plasma ranolazine levels. The peak plasma ranolazine levels are typically achieved at from about 30 minutes to eight hours or more after initially ingesting the dosage form while trough plasma ranolazine levels are achieve at about the time of ingestion of the next scheduled dosage form. It is preferred that the sustained release dosage forms of this invention are administered in a manner that allows for a peak ranolazine level no more than 8 times greater than the trough ranolazine level, preferably no more than 4 times greater than the trough ranolazine and most preferably no greater than 2 times trough ranolazine level.
The sustained release ranolazine formulations of this invention provide the therapeutic advantage of minimizing variations in ranolazine plasma concentration while permitting, at most, twice-daily administration. The formulation may be administered alone, or (at least initially) in combination with an immediate release formulation if rapid achievement of a therapeutically effective plasma concentration of ranolazine is desired or by soluble IV formulations and oral dosage forms.